<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
#div1 {width:200px; height:200px; background:red; filter:alpha(opacity:30); opacity:0.3;}
</style>
<script>
window.onload=function ()
{
	var oDiv=document.getElementById('div1');
	
	oDiv.onmouseover=function ()
	{
		startMove(100);
	};
	oDiv.onmouseout=function ()
	{
		startMove(30);
	};
};

var alpha=30;
var timer=null;

function startMove(iTarget)
{
	var oDiv=document.getElementById('div1');
	
	clearInterval(timer);
	timer=setInterval(function (){
		var speed=0;
		
		if(alpha<iTarget)
		{
			speed=10;
		}
		else
		{
			speed=-10;
		}
		
		if(alpha==iTarget)
		{
			clearInterval(timer);
		}
		else
		{
			alpha+=speed;
			
			oDiv.style.filter='alpha(opacity:'+alpha+')';
			oDiv.style.opacity=alpha/100;
		}
	}, 30);
}
</script>
</head>

<body>
<div id="div1"></div>
</body>
</html>
